The fee is believed to be an initial £2.5 million rising to a maximum of £3.25 million.

Brighton manager Gus Poyet commented on the signing: “He is a player that we can build our team around, which is why I was so keen to bring him here, and one of the most pleasing aspects for me is that we have signed him despite interest from some other big, big teams.”

Posh owner Darragh MacAnthony commenting on his Twitter page said: “It’s not up to me where any player goes, I accept right bid for our club, then player makes decision where he goes. Let’s move on.”

Mackail-Smith has shunned interest from Premier League clubs and Championship favourites West Ham as well as Leicester to move to Brighton.